5,253 research outputs found

    State-Space Interpretation of Model Predictive Control

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    A model predictive control technique based on a step response model is developed using state estimation techniques. The standard step response model is extended so that integrating systems can be treated within the same framework. Based on the modified step response model, it is shown how the state estimation techniques from stochastic optimal control can be used to construct the optimal prediction vector without introducing significant additional numerical complexity. In the case of integrated or double integrated white noise disturbances filtered through general first-order dynamics and white measurement noise, the optimal filter gain is parametrized explicitly in terms of a single parameter between 0 and 1, thus removing the requirement for solving a Riccati equation and equipping the control system with useful on-line tuning parameters. Parallels are drawn to the existing MPC techniques such as Dynamic Matrix Control (DMC), Internal Model Control (IMC) and Generalized Predictive Control (GPC)

    Matrix Product States, Random Matrix Theory and the Principle of Maximum Entropy

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    Using random matrix techniques and the theory of Matrix Product States we show that reduced density matrices of quantum spin chains have generically maximum entropy.Comment: 11 pages, 4 figure

    Are Rural People more Anti-Immigrant than Urban People? A Comparison of Attitudes toward Immigration in the U.S.

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    Immigration to the United States has increased markedly in the past two decades, including significant growth in rural areas. Using General Social Survey data we compare rural and urban attitudes toward immigration in the United States. Our analyses reveal that, first, overall opposition is more pronounced in rural areas. Second, notions of a distinct American identity matter for urban, but not rural, residents. Third, beliefs about immigration are salient predictors in both regions. Fourth, political ideology is a determinant exclusively among rural residents, whereas political affiliation is a determinant solely among urban residents. Fifth, race and education level are significant determinants of immigration attitudes among both rural and urban individuals. Finally, when holding key factors constant, community residence does not predict immigration attitudes. Our findings suggest cohesion among Americans when it comes to beliefs about the costs of immigration, yet differences between rural and urban regions shaped by American identity and political persuasion

    American Identity and Attitudes Toward English Language Policy Initiatives

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    Relatively little is known about what individual-level factors drive Americans\u27 attitudes toward offering services to immigrants. Using national-level data and logistic regressions, we examine what factors co-vary with whether respondents agree or disagree with specific policy initiatives regarding support for English language use for immigrants. We then examine what factors are related to whether respondents agree that tax money should be used to fund English classes for immigrant children and adults. We find that age, race, and general warmth toward undocumented immigrants predict English-only attitudes, and that marital status, education, and warmth toward undocumented immigrants predict attitudes toward the use of public funds to teach English

    Representational organization of novel task sets during proactive encoding

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    Recent multivariate analyses of brain data have boosted our understanding of the organizational principles that shape neural coding. However, most of this progress has focused on perceptual visual regions (Connolly et al., 2012), whereas far less is known about the organization of more abstract, action-oriented representations. In this study, we focused on humans{\textquoteright} remarkable ability to turn novel instructions into actions. While previous research shows that instruction encoding is tightly linked to proactive activations in fronto-parietal brain regions, little is known about the structure that orchestrates such anticipatory representation. We collected fMRI data while participants (both males and females) followed novel complex verbal rules that varied across control-related variables (integrating within/across stimuli dimensions, response complexity, target category) and reward expectations. Using Representational Similarity Analysis (Kriegeskorte et al., 2008) we explored where in the brain these variables explained the organization of novel task encoding, and whether motivation modulated these representational spaces. Instruction representations in the lateral prefrontal cortex were structured by the three control-related variables, while intraparietal sulcus encoded response complexity and the fusiform gyrus and precuneus organized its activity according to the relevant stimulus category. Reward exerted a general effect, increasing the representational similarity among different instructions, which was robustly correlated with behavioral improvements. Overall, our results highlight the flexibility of proactive task encoding, governed by distinct representational organizations in specific brain regions. They also stress the variability of motivation-control interactions, which appear to be highly dependent on task attributes such as complexity or novelty.SIGNIFICANCE STATEMENTIn comparison with other primates, humans display a remarkable success in novel task contexts thanks to our ability to transform instructions into effective actions. This skill is associated with proactive task-set reconfigurations in fronto-parietal cortices. It remains yet unknown, however, how the brain encodes in anticipation the flexible, rich repertoire of novel tasks that we can achieve. Here we explored cognitive control and motivation-related variables that might orchestrate the representational space for novel instructions. Our results showed that different dimensions become relevant for task prospective encoding depending on the brain region, and that the lateral prefrontal cortex simultaneously organized task representations following different control-related variables. Motivation exerted a general modulation upon this process, diminishing rather than increasing distances among instruction representations

    Adsorption of proteins to thin-films of PDMS and its effect on the adhesion of human endothelial cells

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    This paper describes a simple and inexpensive procedure to produce thin-films of poly(dimethylsiloxane). Such films were characterized by a variety of techniques (ellipsometry, nuclear magnetic resonance, atomic force microscopy, and goniometry) and used to investigate the adsorption kinetics of three model proteins (fibrinogen, collagen type-I, and bovine serum albumin) under different conditions. The information collected from the protein adsorption studies was then used to investigate the adhesion of human dermal microvascular endothelial cells. The results of these studies suggest that these films can be used to model the surface properties of microdevices fabricated with commercial PDMS. Moreover, the paper provides guidelines to efficiently attach cells in BioMEMS devices.Fil: Chumbimuni Torres, Karin Y.. The University of Texas at San Antonio; Estados UnidosFil: Coronado, Ramon E.. The University of Texas at San Antonio; Estados UnidosFil: Mfuh, Adelphe M.. The University of Texas at San Antonio; Estados UnidosFil: Castro Guerrero, Carlos. The University of Texas at San Antonio; Estados UnidosFil: Silva, María Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Negrete, George R.. The University of Texas at San Antonio; Estados UnidosFil: Bizios, Rena. The University of Texas at San Antonio; Estados UnidosFil: Garcia, Carlos D.. The University of Texas at San Antonio; Estados Unido

    Effect of Sunflower and Marine Oils on Ruminal Microbiota, In vitro Fermentation and Digesta Fatty Acid Profile

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    Funding This work has been funded by Consejería de Educación, Junta de Castilla y León (research project LE007A07). Acknowledgments We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). Support received from CICYT project AGL2005-04760-C02-02 is gratefully acknowledged.Peer reviewedPublisher PD

    Biodiversity of forage fishes in the Lower Laguna Madre, southernmost Texas

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    Coastal estuarine ecosystems serve as nursery habitats for many commercially and recreationally important fishes. Biodiversity is a structural indicator and has been used as a metric for conservation and management. In the hypersaline Lower Laguna Madre of Texas, a variety of organisms makes their living in and around the dominant seagrass vegetation. This study provides a general assessment of forage fishes biodiversity collected seasonally with bag seines in two sites: Holly Beach (HB) and South Bay (SB) within the most southern Texas bay system as part of a broader study on fish biology. A total of 15,880 fishes representing 32 species were collected during four quarterly samplings through a year (11,795 from HB and 4,085 from SB). Both sites are interconnected as no fishes similarities difference were found, nonetheless, the sites’ variable characteristics (i.e. basin area, seagrasses coverage, connection to the Gulf of Mexico) resulted in significant greater species richness, relative abundances, and diversity in HB than SB for most of the year, suggesting differences in habitat quality or at the very least variation in the availability of habitat types, which are known to contribute to differences in fish diversity attributes. - Los ecosistemas de estuarios costeros sirven como hábitats de crianza para muchos peces de importancia comercial y recreativa. La biodiversidad es un indicador estructural y se ha utilizado como métrica para la conservación y la gestión. En la hipersalina Laguna Madre Inferior de Texas, una variedad de organismos vive en y alrededor de la vegetación de pastos marinos dominante. Este estudio proporciona una evaluación general de la biodiversidad de peces de forraje recolectados estacionalmente con redes de cerco en dos sitios: Holly Beach (HB) y South Bay (SB) dentro del sistema de bahías al sur de Texas, como parte de un estudio más amplio sobre la biología de peces. Durante cuatro muestreos trimestrales a lo largo de un año, se recolectaron un total de 15.880 peces (11.795 de HB y 4.085 de SB) que representan 32 especies. Ambos sitios están interconectados, ya que no se encontraron diferencias en las similitudes de peces; sin embargo, las características variables de los sitios (es decir, área de la cuenca, cobertura de pastos marinos, conexión con el Golfo de México) dieron como resultado una riqueza de especies, abundancias relativas y diversidad significativamente mayores en HB que en SB durante la mayor parte del año, lo que sugiere diferencias en la calidad del hábitat o, al menos, variación en la disponibilidad de tipos de hábitat, que se sabe que contribuyen a las diferencias en los atributos de diversidad de peces

    The disconnect between knowledge and perceptions: A study of fishermen’s local ecological knowledge and their perception of the state of fisheries and how these are managed in the Dominican Republic

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    Understanding what fishers know about the ecology of the fish they catch, and how they perceive the state and management of their fisheries can guide efforts towards more sustainable fishing practices. We tested relationships between fishers’ local ecological knowledge (LEK) and their perceptions of their fisheries and of marine protected areas in the Dominican Republic. A qualitative-quantitative methodological sequence using data from interviews with 152 multi-species fishers revealed variable, but generally high levels of LEK, particularly of habitat use and predator–prey interactions. The majority reported negative perceptions of the state of their fishery and were aware of local management actions. Contrary to study expectations, we found that fishers’ LEK, measured by Cultural Consensus Analysis, did not significantly co-vary with their perceptions of the state of fisheries or with their awareness of, and support for, marine protected areas. These results highlight the need to identify and understand barriers to information flow and communication in local fisheries’ social/political networks
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